Paleoenvironmental reconstruction of Holocene peatlands in the lower Ribeira do Iguape River, São Paulo.

• Grant number: 24/14874-7
• Support Opportunities: Scholarships in Brazil - Support Program for Fixating Young Doctors
• Effective date (Start): September 01, 2024
• Effective date (End): August 31, 2025
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Acordo de Cooperação: CNPq
• Principal Investigator: Pablo Vidal Torrado
• Grantee: André Luiz Miranda Reis
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 24/02144-4 - Paleoenvironmental reconstruction of Holocene peatlands in the lower Ribeira do Iguape river - SP, AP.R

Abstract

Peatlands are wetland ecosystems predominantly constituted by the presence of Histosols, formed due to the maintenance of conditions unfavorable to the decomposition of organic matter. They play a crucial role in ecosystem functions, such as storing large carbon stocks, despite covering only 3% of the Earth's surface; they store a third of all soil carbon. In the lower Ribeira do Iguape River (BRRI) in São Paulo state (SP), Histosols occupy approximately 70,000 hectares, representing one of the largest occurrences of these soils in South America. In a recent pilot study (the doctoral thesis of the proposer) conducted in the Campina do Encantado State Park (PECE), in the municipality of Pariquera-Açu (SP), the research team developed and applied advanced protocols for sampling, characterization, and mapping of organic soils for various studies. Based on this experience, a research grant (FAPESP Grant 2023/04708-0) was submitted and approved to fund the proposed activities. The project aims to continue paleoenvironmental reconstruction studies in other peatlands of BRRI (one of the objectives of the research grant), seeking to understand whether these peatlands formed in estuarine-fluvial and/or fluvial-continental environments. Additionally, the study aims to contribute to understanding the influence of sea level variations on the formation of Holocene peatlands on the southern coast of SP. Thus, the hypothesis is posited that the peatlands of BRRI are Holocene in origin and formed after the beginning of the last marine regression, predominantly under fluvial influence. The brackish environment in which paludification occurred gradually transitioned to freshwater over time. The vegetation and genesis of Histosols appear to be conditioned by a gradient from continental to coastal conditions. The history of peatlands will be reconstructed through the integration of indicators, including their relationship with shell mounds, pollen grains, algae, diatoms, dinoflagellates, palynoforaminifers, ´13C and ´15N isotopes, radiocarbon dating, and geochemical analysis of different peatlands distributed in BRRI. This research is expected to enhance understanding of peatland formation in near-sea-level environments and their role in the current scenario of climate change. (AU)